Busan (South Korea): US Secretary of State Hillary Clinton on Wednesday voiced regret that Pakistan had announced a boycott of a meeting on Afghanistan in Germany and urged it to consider.

Speaking at an aid conference in South Korea, Clinton reiterated the US stance that the border killing of Pakistani soldiers was a "tragic incident" and pledged an investigation "as swiftly and thoroughly as possible."

"Frankly this is regrettable that Pakistan has decided not to attend the conference in Bonn because this conference has been long in the planning," Clinton told reporters.

"Pakistan like the United States has a profound interest in a secure, stable and increasingly democratic Afghanistan," Clinton said.

Clinton voiced hope that Pakistan would find a "follow-up way" to take part in talks on Afghanistan's future.

NATO air strikes killed 24 Pakistani troops on the Afghan border in disputed circumstances, inflaming new tensions between Islamabad and the West.